The present invention is directed at the field of guidewires. Specifically, the present invention concerns a guidewire having a radiopaque tip.
Generally, guidewires include one or more coil springs fixed about a solid or tubular central core wire. Usually, the distal end of the guidewire is shapeable. This shapeability allows the surgeon to bend the distal end before insertion in the vascular system in conformance with the tortuous pathway of the desired vascular system segment through which the guidewire is being manipulated.
Guidewires are principally used for manipulating catheters through a patient's vessels, i.e. blood vessels. One specific application is the proper placement of a catheter in a patient's vascular system for a procedure known as percutaneous transluminal coronary angioplasty (PTCA).
A typical PTCA procedure involves percutaneously inserting a guiding catheter distal tip into the cardiovascular system of a patient and advanced therein until the distal tip thereof is in the coronary artery. A guidewire is introduced through the guiding catheter and advanced into the patient's coronary vasculature until the distal end of the guidewire crosses the lesion to be dilated. A dilatation catheter having an inflatable balloon on the distal portion thereof is advanced over the previously introduced guidewire, with the guidewire slidably disposed within an inner lumen of the dilatation catheter, until the dilatation balloon is properly positioned across the lesion. Once in position across the lesion, the balloon is inflated to a predetermined size with radiopaque liquid at a relatively high pressure to compress the atherosclerotic plaque of the lesion against the inside of the artery wall. The balloon is then deflated so that the dilatation catheter can be removed and blood flow resumed through the dilated artery.
Examples of guidewire designs are disclosed in U.S. Pat. Nos. 4,545,390, issued to Leary on Oct. 8, 1985; 4,538,622, issued to Samson on Sep. 3, 1985; 3,789,841, issued to Antoshkiw on Feb. 5, 1974; 4,815,478, and 4,813,434, both of which issued to Buchbinder et al on Mar. 28, 1989 and Mar. 21, 1989, respectively; 4,922,924, issued to Gamble et al on May 8, 1990; 4,763,647, issued to Gambale on Aug. 16, 1988; 4,846,186, issued to Box on Jul. 11, 1989; and 4,886,067, issued to Palermo on Dec. 12, 1989, with the disclosures of such references concerning the description of the guidewire being incorporated herein by reference.
Numerous workers have devised guidewires to increase the steerability through the coronary system. For example, the tips are made more flexible by terminating the distal end of the core wire short of the distal end of the helical coil spring. A second inner helical coil spring is brazed at one end to the distal end of the core wire and at its opposite end to the distal end of the outer helical coil spring, see Gambale U.S. Pat. No. 4,763,647 and Palermo U.S. Pat. No. 4,886,067.
Steering of the guidewire through the patient's coronary system is usually accomplished by viewing the guidewire via X-Ray. Visibility of the guidewire is achieved by forming at least a portion of the guidewire from a radiopaque material. This may be accomplished by many different ways. For example, a radiopaque spring is mounted to the end of the guidewire as disclosed in U.S. Pat, No. 4,538,622. Other examples include forming the entire guidewire from a radiopaque spring.
While existing guidewires provide adequate steerability and radiopaqueness, further improvements are desirable.